save_note · NestJS MCP Server MCP: Risk & Policy

WHAT IT DOES

What save_note does on NestJS MCP Server

AI agents use save_note to create or update resources in NestJS MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your NestJS MCP Server environment.

WHY IT NEEDS A POLICY

Why save_note needs a policy

This tool creates or updates notes in storage, fitting the Write category (creates/modifies data reversibly). The severity is medium because misuse could result in modified note data, but notes are typically low-risk compared to financial or system-critical data. Given the NestJS/DDD context suggesting a note management system, this appears to be application-level data modification without destructive capability.

From the tool's definition Tool description indicates 'save_note' saves key-value pair memos. The verb 'saves' and the functional context of persisting data to storage demonstrates a write operation that creates or modifies data reversibly.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

save_note Rate-limited

save_note stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "save_note": {
      "limits": [
        {
          "counter": "save_note_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches NestJS MCP Server, so you can run agents against it safely.

FAQ

Questions about save_note

What does the save_note tool do? +

キーと値のペアでメモを保存します. It is categorised as a Write tool in the NestJS MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on save_note? +

Register the NestJS MCP Server MCP server in PolicyLayer and add a rule for save_note: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches NestJS MCP Server. Nothing to install.

What risk level is save_note? +

save_note is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit save_note? +

Yes. Add a rate_limit block to the save_note rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block save_note completely? +

Set action: deny in the PolicyLayer policy for save_note. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides save_note? +

save_note is provided by the NestJS MCP Server MCP server (kaz29/mcp-server-example). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.